EKG Findings and Localization of Injury

Pathophysiology of ST Depression

In resting/repolarized state the ischemic area is depolarized and generates electrical currents towards the overlying leadsT-P and P-R segments are actually shifted “up” in resting stateThus when entire ventricle is depolarized it appears that the ST segment is “depressed”

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Pathophysiology of ST Elevation

In resting/repolarized state the ischemic area is depolarized and generates electrical currents away from the overlying leadsT-P and P-R segments are actually shifted “down” in resting stateThus when entire ventricle is depolarized it appears that the ST segment is “elevated”

Pathological Q Wave Determination

Therefore Q wave with no ST elevation, not acute occurrence but it happened sometime

If Q wave + ST elevations then acute

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T Waves

T wave is ventricular repolarization and every lead, the QRS and T wave should go in the same directionThis occurs because repolarization occurs in opposite direction of depolarization

T wave inversions occur in lead when polarity between the two is not correlatingWhen associated with ischemia they:Are usually inverted (symmetrically) or biphasicMay help with localization to a particular portion of the left ventricle (but not as predictive as Q waves and ST elevation)

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U Waves

Occurs right after T WaveBest seen in V2 and V3Rarely seenOften seen with bradycardiaPathological if: > 1.5 mm in height or Inverted (ischemia)